Fuel-economizer.



E. H. FOSTER.

FUEL ECONOMIZER.

APPLICATION FILED FEB. 17,1916.

PatentedSept.4,1917.

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UNITED STATES PATENT OFFICE;

ERNEST H. FOSTER, 0F DON GAN HILLS, NEW YORK, ASSIGNOR TO POWER SPECIALTY COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

FUEL-EcoNoMIzER.

mizer so that the feed water is introduced atthe top thereof and by aid of its gravity zigzags back and forth. across and downward 'in counter current to the rising gases, the-highest temperature of the feed "water 1 n said economizer being at the point where 1t enters the boiler proper.

Another of the more important features of the invention consists in employing independent cast metal rings in contact with each other and fitting snugly on the economizer tubes so that theE-absorptiqn of heat energy of the gases of combustion by. the water flowing through the economizer tubes will be as complete as possible. This means that the heat must pass from the gases to the metal comprising the tube and thencefrom the metal .to the water. The rateof heat transference between a gas and a metal differs from the rate between water and a metal, being much greater in the latter case. In order to compensate for this diiference it is necessary to provide a larger contact surface between the gas and the metal, where the transference is slow, than between waterand the metal where the transference is relati vely rapid. Thus by providing an economizer tube with a large external as compared with internal surface, a higher eiiiciency or transf erence capacity is obtained than if ordinary cylindrical wall tubes were used, as has been the custom heretofore This construction permits the use of two kinds of metals in making'economizer tubes which in turn enables the application of economizers to high steam pressures. Economizer tubes as now commonly employed are made from cast iron because the resistance of the latter to attacks from gases of combustion and from the corrosive or pitting tendency of hot water which passes through the tubes. Cast iron tubes are not reliable unless made with relatively thick walls 7 Specification of Letters Patent.

the further result 'terior-which has said Patented Sept. 4, 1917.

Application'flled February 17, 1916. Serial No. 78,799.

which implies more weight and requires more space than if a more reliable or stronger metal is used. On the other hand tubes madefrom the stronger and more reliable metals, such as steel and wrought iron, have proven unsuccessful as economizers because of their short life due to the corrosive efiect of gases and water. Then again modern practice is constantly requiring higher steam pressures and up to approximately 200 lbs. per square foot cast iron economizers have een used successfully, but at higher pressures cast iron is unreliable for this purpose,

with a result that one is forced to use steel or wrought iron tubesor else abandon the use of economizers entirely, which would not only be a serious loss to power plant economy but necessitates the burning of more fuel. My invention therefore contemplates the use of non-corrodible tubes, such as copper or brass, covered with cast iron external protection surfaces with the beneficial result of the Water, which has a corrosive action, coming into contact with a non-corrodible surface forming the body of the tube, and with that the gases of combust1on come in contact with the cast iron exexcellent durability or resistance against the detrimental action of gases.- 7 Another feature of my invention consists in arranging the economizer in sections so that each section is independently removable, .or removable with the corresponding boiler section. I

In the drawings: Figure 1 is a cross-section of a boiler construction with my invention embodied therein.

Fig. 2 is an end view economizer tubes.

Fig. 3 is a horizontal 33 of Fig.1..

Referring to the drawings in detail the reference numeral 10 designates a type of boiler illustrating one application of my invention this particular type being selected because of its simple construction thus making the invention and its useful application easily comprehended. The boiler setting is provided with a furnace 11, a passage 12 in of a portion of the view taken on line the rear thereof for the escape of gases from.

boiler proper is composed of a plurality of boiler. sections each section comprising an inlet header 1 1, an outlet header 15, and con- .necting tubes 16. The setting is also proand forth across and downward in a direction opposite to the flow of furnace gases through said passage 12. These sections of tubes are provided with supports 19, with" inlets 20, a feed water pipe 21 connected to .said inlets, and connections 22 to the inlet header 14. y p

The tubes 18 are provided with a cast metal covering preferably in the form of a series of independent, continuous cast metal tapered rings in contact with each other. which are employed as a protection for the tubes and to absorb -additional heat energy from the waste gases from the furnace.

The arrangement of the economizer tubes.

in zigzag fashion so that the flow of feed water is to and fro across'the passage 12 results in a gravity feed of the feedwater through the economizer tubes into the inlet header of the boiler, and this horizontal arrangement, furthermore, avoids the development of air pockets in said economizer tubes. Any section may be removed for the purpose of repair or replacement'without disturbing other sections. This removal of a section is also desirable when a come sponding section of the boiler tubes requires removal, when they may be removed together.

From the above description it will also be seen that I have devised a simple form of economizer for boilers which is not only capable of withstanding the corrosive ac tion of the water on the interior thereof but also capable of withstanding the corrosive action of the gases of combustion on the exterior thereof. Furthermore, my invention also embodies the economical feature of an economizer composed of two metals which I are constructed and arranged to compensate for the relatively different rates of heat transference between the gases of combustion and the tube on the one hand andthe' tube and feed water on the other hand. The use ofthe two metals mentioned, or their equivalents, in the construction of the tubes and in the manner indicated lessens the cost of the metals over the cost of the ordinary economizer tubes and at the same time there results not only a lighter tube, that is, one containing less metal, but a tube. for the purpose which is materially stronger than the tubes now in vogue.

It will be understood that I do not limit myself to the exact construction and composition of parts shown and described as the drawing is merely an illustrative one and the invention is capable of other embodiments without deviating from the true spirit and scope of my invention.

What I claim is:

1. A boiler having a plurality of individual boiler sections comprising headers and boiler tubes connecting said headers and also having a vertical passage for the furnace gases beyond said section, in combination with an economizer composed of a plurality of individual sections vertically arranged in said passage and installed between the boiler and'smoke stack, the tubes of said economizer being vertically arranged with respect to the flow of the furnace gases and the inlet and outlet to said economizer being at the top and bottom respectively, whereby water circulates by aid of its own. gravity through said economizer, said economizer sections being individually connected to said boiler sections whereby one boiler section and one economizer section may be removed for repair or replacement without disturb: ing the other sections.

2. A .boiler comprising a plurality of boiler sections and a vertical passage for the escape of furnace gases located in the rear of said sections, in combination with an economizer vertically arranged in said passages and consisting of a plurality of sections each individually connected to said boiler sections and each individually removable with one of said boiler sections.

In testimony whereof I hereunto afiix my signature.

" ERNEST H. FOSTER. 

